With the recent spread of various small-sized electronic equipment including personal computers, it has come to be required that a plurality of coaxial cables are wired so as to match characteristic impedance with high precision in narrow space. In order to meet such a requirement, for each of the plurality of coaxial cables, it has become necessary that an outer conductor (shielding layer) is surely grounded, and that a central conductor is securely connected to each of determinedly spaced connector terminals or a circuit of a substrate.
For that purpose, it has come to connect the cables together, using a flat cable in which the plurality of coaxial cables are arranged at determined intervals and adhered to tapes. However, the problem has arisen that the thinner coaxial cables results in lower strength of connected portions.
As a means for solving such a problem, a process is proposed which comprises e sing shielding layers in the vicinity of end portions of a plurality of coaxial cables, fixing two pair of ground bars (metal foils) to the shielding layers with solder, bending the cables taking an approximately intermediate portion between the two pairs of ground bars as a fulcrum to cut the shielding layers, thereafter removing the shielding layers together with the metal ground bar on the end portion side to expose insulating layers (dielectric layers), adhering plastic tapes to the insulating layers by melting to fix respective insulating cores at determined intervals, followed by cutting the insulating layers with a laser beam, shifting the insulating layers of the end portions in a direction to remove them to expose central conductors, cutting off end side portions including the plastic tapes, and coating end portions of the central conductors with solder (Japanese Patent Unexamined Publication No. 10-144145).
However, in such a conventional process, the metal ground bars are fixed to the exposed shielding layers with solder in the vicinity of the end portions of the plurality of coaxial cables, so that the solder flows out of the metal ground bars to the shielding layers. Moreover, the two pairs of metal ground bars are provided, and the cables are bent, taking an approximately intermediate portion between the two pairs of ground bars as a fulcrum to cut the shielding layers, followed by removing the shielding layers together with the metal ground bar on the end portion side. As shown in FIG. 5, therefore, a solder layer 6 containing the shielding layers 3 such as served wire shielding layers protrudes and remains at end faces S of the metal ground bars 5 left on the side of the plurality of coaxial cables 1. Accordingly, connection thereof to a connector becomes difficult, and the use for applications in which high voltage is applied allows current to leak between the shielding layers 3 and the central conductor 8 to cause poor insulation in some cases. The incidence of defective products has therefore amounted to a value as high as 30% to 40%.
Furthermore, the two pairs of metal ground bars are used, and of these, the one pair on the end portion side are removed and discarded together with the shielding layers, resulting in high cost.